On the Understanding of Defects in Short-Term Negative Bias Temperature Instability (NBTI) for Sub-20-nm DRAM Technology

Short-term Negative Bias Temperature Instability (NBTI) was investigated in sub-20-nm DRAM technology. By using Variable $\text{T}_{\text {charge}}$ - $\text{T}_{\text {discharge}}$ Amplitude Charge Pumping measurement, ultra-fast traps can be characterized with high accuracy. Both electron traps and hole traps are identified in the transistor. The energy and spatial distribution for these two traps can be clearly extracted. By further comparing with ab-initio calculation, the electron traps are found to relate to dangling bonds and hole traps originate from oxygen vacancies. Electron traps can contribute up to 90% in short-term NBTI and thus could be critical for future improvement. The results are useful in understanding the reliability of sub-20nm DRAM technology.